The present invention generally relates to a method of removing one or more color constituents from a dairy material, such as a whey material, to produce a reduced color dairy product, such as a reduced color whey product. More specifically, the present invention relates to a method of processing a dairy material, such as a whey material, to produce a reduced color whey product by separating a coloring agent from the whey material and optionally deactivating the coloring agent.
More than 140 million tons of fluid whey is produced worldwide annually. Coagulation of milk, such as whole milk, yields solid curds and a watery portion that is commonly referred to as fluid whey. Fluid whey is an opaque, greenish-yellow fluid that typically contains about 5 to 7 weight percent total solids and 90 weight percent or more water. The solids includes fats, soluble and insoluble proteins, carbohydrates, and ash.
Fluid whey has a very high biological oxygen demand (BOD). Because of the high BOD, disposal of fluid whey by application to land or in water courses, such as creeks and rivers, is typically illegal in most civilized countries. Furthermore, treatment of fluid whey in wastewater treatment plants to reduce the BOD level is relatively expensive. The inherent difficulties that fluid whey disposal creates have resulted in development of processing techniques that render the fluid whey, or components of the fluid whey, useful in preparing food products for human and animal consumption.
The protein portion of whey materials, such as fluid whey and whey protein concentrate, is a high value food component and additive. However, during the production of certain types of dairy products, such as cheddar, Colby, and Cheshire cheeses, coloring agents, such as dyes and extracts, are typically added for purposes of providing the dairy product, such as cheddar cheese, with a particular color. The coloring agent may be added because the colored food product is viewed as having desirable characteristics by the consuming public by virtue of the color. Also, certain dairy products, such as cheddar cheese, may be provided with a particular color to create a particular grade or style of product that is capable of being readily recognized by the consuming public. As an example, annatto extract, a natural coloring material derived from the bixo orellena fruit, is typically added during the manufacture of certain types of cheese to give the cheese a color which the consumer has come to expect and accept. Other non-exhaustive examples of food coloring agents that are added or could be added for purposes of colorizing dairy products include .beta.-carotene, apo-8-carotenal, canthaxanthin, paprika oleoresin, turmeric, and beet extract.
However, though the addition of coloring agents to give particular dairy products particular colors is beneficial and, indeed very important, for purposes of marketing the product to the consuming public, there is an undesirable consequence due to this coloring agent addition. Specially, the byproduct whey materials that remain following production of the initial dairy product retain some amount of the coloring agent and are thereby colorized. As noted above, these byproduct whey materials are typically processed for purposes of making an additional product out of the whey material or components of the whey material.
The coloring agent in the byproduct whey materials causes products that are based on the byproduct whey materials to be colorized. In many cases, this is undesirable. For example, when byproduct whey material is further processed to form baby formula, the purchasers of baby formula may not buy the baby formula if the baby formula is based upon whey material containing annatto extract and is consequently colored orange. In essence, though a color may be beneficial or desired for one particular type of dairy product, it may be highly undesirable for another dairy product based upon byproduct whey material to have the color of the initial dairy product. Therefore, while there is value to adding coloring agents to some dairy products, there is likewise value to removing coloring agents from byproduct whey materials derived from manufacture of colored dairy product, prior to or during production of another product from the byproduct whey materials.
One method for decolorizing whey material is mentioned by Chang et al. in Reactions of Benzoyl Peroxide with Whey that appeared in J Dairy Science, Vol. 60, pp 40-44 (January, 1977). Chang et al. mentioned that hydrogen peroxide or benzoyl peroxide may be added to whey that is a byproduct of cheese manufacture to give wheys colored with annatto extract "a more uniform color." However, as mentioned in Chang et al., the electrophoretic pattern of the whey proteins was altered by bleaching the whey containing the proteins with benzoyl peroxide. It is believed that this change in the electrophoretic pattern of the whey protein is indicative of denaturing of soluble whey proteins that occurs when protein-containing whey is bleached with an oxidizing agent, such as benzoyl peroxide.
U.S. Pat. No. 4,888,184 to Bottomley et al. also describes a process in which hydrogen peroxide is added to a whey material containing a significant or even concentrated amount of protein, including soluble protein, for purposes of oxidizing annatto extract included in the whey. However, it has been found that the technique of modifying whey color disclosed in the Bottomley patent, like the process mentioned in the Chang article, alters the electrophoretic pattern of the whey proteins, apparently by denaturing soluble proteins contained in the whey.
Denaturing of soluble proteins in whey materials is undesirable, since soluble proteins constitute a significant and valuable portion of the protein spectrum present in many whey materials. There is therefore an urgent need for a method of decolorizing whey materials containing soluble proteins along with coloring agents, such as annatto extract, without altering the soluble proteins that are contained in the colored whey material. Thus, a need exists for preserving the valuable soluble protein portion of whey materials while ridding the whey materials of undesirable color deriving from coloring agents, such as annatto extract.